Signaling system



Feb. 13, 1923. 1,443,141

, V B, W. KENDALL SIGNALING SYSTEM filed Dec. 18, 1916 0 WM for: Barron W. Kehda/L Patented Feb. 13, 1925.

UNITED STATES PATENT OFFICE.

BURTON W. KENDALL, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN CIILEC'IRH'. COMPANY, -"I'NCORPOBATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.'

SIGNALING SYSTEM.

Application filed December 18, 1916.

transmitted over a single hlgh-trequency line. The features of the invention are, in generah'applicable also to radio transmis sion in which case the line would be replaced by an antenna. Each carrier wave is modue lated by a signal which originates in a low- '20i frequency line, a plurality of which are associated with the high-frequency line.

The object of the invention is to secure a two-way transmission of signals between the single high-frequency line and all of the low-frequency lines.

The invention provides for balancing the high-frequency line at all of the various carrier frequencies and at the audio-trequencies used, and each low-frequency line is balanced at telephonic frequencies. Between the high-frequency line and the lowfrequency lines are connected modulating and detecting circuits for changing the lowfrequency messages into high-frequency messages, and vice versa, and means for isolating and transmitting the audio-frequ'ency message. The modulating circuits and the detecting circuits are connected in conjugate relation to the high-frequency line and its balancing net work so that a modulated carrier wave will be sent out upon the highfrequency line without affecting the local detecting circuit. The transmitting circuits for the low-frequency message are similarly placed in conjugate relation, in

the ordinary t-woway repeating circuit.

The figure shows diagrammatically a system for carrying out the invention.

In the figure, the line 1 is adapted to send )0 and receive an audio-frequency message and also a plurality of modulated carrier waves. The low-frequency lines 2. 3 and 40 are each adapted to send and receive a low'f1-equency signal. Between the high-frequency line 1 and the low-frequency lines 2, 3 and Serial No. 137,592.

40 are connected suitable means which provide for the two way transn'iission of signals. Connected in the high-frequency line 1 are the coils 4 and 5, across the mid-points of which is bridged the line 6, associated with the modulating circuits M and M and the low-frequency repeating circuit 'R,. In the high-frequency line 1 is also connected the high-frequency net work or artificial line 7, which simulates the impedance of the high-frequency line 1 at all of the carrier and audio-frequencies transmitted over the line 1. The high-frequency net Work 7 may consist of a serially connected resist ance and condenser, as shown in the patent to Hoyt, No. 1,167,694, January 11, [1916, Artificial line. Inductively related with the coils 4 and 5, is the coil 8, connected in the line 9 with which are associated the detecting circuits D D and the low-frequency repeating circuit R 7 In the detecting circuit D is the resistance 10 connected across the line 9. This resistance serves as a source of potential for one or more an'iplificrs A, of the audion type. The grid 11 of this amplifier is maintained at a suitable negative potential by means of a battery 12. Space current is supplied in the output circuit of the amplifier A through the impedance 13 by the battery 14. The condenser 15 prevents current from the battery 14- irom flowing through the filter F which selectively transmits the carrier frequency designed for the detecting circuit I) he fitter I selectively transmits a modulated carrier wave of a given 'irequency to the detector (1 which may be a thermionic detector as shown. The output circuit of the detector Z is coupled by means of the transformer 16 and coils 1T, 18 and 19 to thelow-frequency line 2. In the low-frequency line '2 are connected the coils 18and 19 and the artificial line 20. Coils 17, 18 and 19 are inductively related, and bridged across the mid-points ot' the coils 18 and 19 is the line 21 which transfers signals originating in the line 2 to the moulating circuit M The modulating circuit M comprises a modulator m of the audion type. in the input circuit of which is connected the secondary Winding of transformer 22, the primary winding of which is connected in the line 21. The higlr'lrequency generator 23. shunted by the resistance 24, is adapted to lllr p current in the output th modulator m issupplicd by irough the impedance 26. scheme is described and liltates patent to Van der granted August 1920, iency signaling. "he concurrent from battery 'ough the resistance 28, source of potential for "s it, The output cir- J l; is tuned to the "fre- 2y generator 23 by means 29. ll'lodulated carrier red from the output cir- A to the loop resonant ofthe transformer 30. ant circuit is serially conind is tuned to the fre- He d by cue generator 23.

ling circuit M associated with line I3 is substantially the lulatin gr circuit ill just deices being that the high- 34- supplies a carrier difi erent From that water 23; also, the outi amplifier A and the loop b are tuned to the freby the gei'lerator Ell. iripiency repeating circuit l l andits-frequency currents einiency line to the line. 1 the l'iigliit'i'equency line 1. ilarly to the lines 2 and 3, eleplonic frequencies. By A in the repeating amplified andio-l requency curplied through the filter F and to the line ii. The filter l iencies above telephonic 'l*re iout ifillfi cycles. iat coil of transformer 35 e G the small condenser les an easy path around this "101 waves from N M etc -reby short-circuiting the cur re l rezpieucies supplied by this i c o'eiu 1 loop resonant circuit is highly selew 'l'rcuuency for which tire for cameras or n it is tuned while oll'ering a path of low in'r euani-e to currents oi dillerent l'rccpienmodulated carrier wave supplied nit 3 and the andio-lrequcucy our .nts from circuit ll, find a path of low impedance through the other loop resonant circuits (7 etc. connected in the line 6. it P l ip-c esonant circuits were not pro carrier ware supplied by circuit nee. would not be ellieiently vo the line '1. as this carrier to ly i v 4- t in, 1Ul)\ c( i all seconr a y -L'Ullllt'l it'll. which transfers Let-45,141

.7 1 the carrier are from circuit M to the line (3.

The modulated carrier waves supplied by the modulating circuits M M and the lowfrequency wave from circuit R, etc.. are conducted hy the line to the mid-points of the coils 4e and 5 The current divides through the coils 4 and 5. one half going through artificial line T. and the other halfgoing out upon the high-trequency line 1. The currents flowing through coils 4 and 5 induce equal and opposing electromotive forces in the two halves of the coil 8. so that the messages are sent out upon the hight'rerplency line 1 in such a manner as not to thereby, afiect the detecting circuits D D, and the repeating circuit R associated with the line. S). The lines 6 and 9 may be interchanged in their connection with the coils 4, 5 and 8 and a similar interchange may he made in the connections of the balancing networks associated with the lowfrecpiency lines 2, 3. 40, etc. If desired, the modulating circuit M and the corresponding detecting circuit D may be designed to use the same carrier *l'rei uency.

The detecting circuits l) are substantially the same the only difference being the adjustment of the Various elements whereby each detecting circuit handles the carrier t'requency generated in its correspomling modulating circuit at a distant station,'not shown. The amplifiers A and A are essentially unilaterally conducting, in order to prevent interaction of the filters F and F which are connected across line 9. \Vhere filters are connected directly in parallel, there is a tendency for the terminal sections oi one filter to act in part as a low impedance for currents of frequencies outside the transmission range of that particular filter. In certain cases this may seriously interfere with effective transmission to the other filters. lliloreorer, transients may be set up by one filter in consequence of electrical disturbances in the common line and these transients may then he applied to otherfilters to cause interfering disturbances to be transmitted thereby. The asynunetric property of the amplifiers prevents retransmission to the common line 9 of transients originating in any particular filter. lvloreover, the high impedance of the input circuits of the amplifiers prevents the individual filter channels from in anywise serving short circuits for each other across line 9.

An ai1die-frequency signal sent from a distant station over line 1 is transferred from line 9 by means of the repeatingcircuit R to the. low-frequency line 40. The resistance 37 and amplifier l are similar to the corresponding elements in the circuits D D The filter F suppresses all frequencies abov telephonic frequen di-ofrequenc y me to the line 40.

; and transmits theaie' and receiving audio frequency waves, between said high frequency line d low frequency lines common to said flequen y lines for the two-way trans- .ii i oi signals.

signaling system comprising a high 11v line for sending and receiving of modulated carrier waves havw'ent carrier frequencies, a balancing Wort-z associated with said high fre- "f' line and comprising; means for impedance of said line at all frequencies, a plurality of dating circuits and correspondim deociated in sonjugate rel: h said hi h frequencv line and haliclng; not .vork, .aii'l pluralit; of low money lines for sending and receiving io-freque waves, each of said I'I'lOtlt.

circuits and its corresponding deg circuit being associated with one of ow irequenc lines.

A signaling s 'stem comprising a highline t sew ling and receiving a line in currents ill" 3, of moan l e 1 Ct rrier waves having 9 ,tl'erent carrier trcquenries, a balancing net oil: associated with said high frequency and 'OIDiH'lSlHQ means for simulating iv-irequenim iedanee ot said line at all of said car- R art not 1' ti qiiencies a plurality of modulating i ire- Ollii'iiltS and corresponding detecting circuits ted in conjugate ation with said ecuoncv hm and balancing; net Work,

3 low frequency lines for sendie'i 'ing audio frequency Waves, i net? work associated with each l frequency lines and comprisartilicial line, each of said modulatircn"s and its cnrresponding detecthei associated in conjugate :h of said low frequency a in, a high frequency sigiancing means for simulatat ordinary telephonic nigh the "frequency range v currents to be transmitted i on thsretm means for in iic'ing currents within ordinary teleihonic 'li-equency range over said signal line. iitting other currents of ii 'iier 'l'requencies over said line, a ,iiflky signal line and balancing simulating the impedance of said 3W frequency line connected thereto, and 1 0 no-way repeater circuits'between said lines shi *equency connected at the points of connection of said 3 line" with their respective balancing means. A IPlllM" system comprising a S1gplurality of resistances said line and an individual iaiing circ' inclnding an asymmetr i condn device connected to two inls i cnmprising a line,

a plurality of resistances shunted across said line. and an individual signaling circuit connected'rto two points of each resistance, each of said signaling circuits including a thermionic repeater.

9. In combination a transmissipn line. a plurality of signaling circuits. each of said signaling circuits being connected to said line by a two way repeater.circuit at least one of said repeater circuits comprising means for modulating a carrier current in accordance with signal currents impressed thereon by the cm'respoiuling signaling (in cuit and another of said repeater circuits comprising means for repeating currents of a single range of frequencies in both directions.

10. A transmission line and a plurality of signaling circuits, each of said signaling circuits being permanently connected to said line by a two-way repeater circuit, said 7 repeater circuits having common points of connection to said line. and means for supplying speech freqi'iency currents for transmission in both directions between said transmission line and one of said signaling circuits.

11. A repeating system comprising a high frequency line. a low frequency line. and means connecting said lines comprising two asymmetric channels transmitting in opposite directionsfone of said channels includ ing means for modifying carrier currents and the other of said channels including means for detecting carrier currents.

12. A high frequency line, an incoming channel and an outgoing channel conjugately connected thereto. a plurality of low frequency lines, and means including a modulato' associated with the outgoing channel and a detector associated with the incoming channel for connecting each of said low frequency lines to said hlgh frequency line.

13. A high frequency line, an incoming circuit and an outgoing circuit conjugately connected thereto, a plurality of signaling lines, means for connecting said signaling lines to said outgoing circuit, and means shunted across said incoming circuit for connecting said signaling line thereto.

14. A high frequency line and a plurality of low frequency lines connected thereto,-at least one of said low frequency lines being connected to said high frequency line by a two-way.repeater comprising a modulator and a detector, and another of said low frequency lines being connected to transmit low fretuiency currents directly to said high frequency line.

15. A line, means for simultaneously transmitting plurality of different frequency speech n'u'idified carrier currents thereover, means for simultaneously transmitting ordinary speech frequency currents thereover, means for balancing said line for.

currents of all the frequencies which it transmits, and conjugate transmitting and receiving circuits associated with said line and balancing means whereby the effect of currents in said transmitting circuit upon their respective local receiving circuits may be minimized.

16. A line. means for transmitting a plurality of different frequency carrier currents of higher than essential speech frequency thereover, means for transmitting speech frequency currents thereover, common means for balancing said line for currents of all the frequei'icies which it transmits, and con-- jugate transmitting and receiving circuits associated with said, line and balancing means whereby the effect of currents in said transmitting circuits upon their lespective local receiving circuits may he minimixed.

1?. A distributing system comprising a plurality of stations. and a periodic transmission line connecting each two adjacent stations for conveying high frequency currents, there being a current of a given high frequency assigned to each station. n'icans at each station for simultaneously transforim ing low frequency currents to currents of the high frequencies assigned to that station, and a low frequency line for each station, each station comprising balancing means for the high frequency assigned to that station. and balancing means for the low frequency currents.

18. A common transmission line, a network connected to said line simulating its impedance at each of the frequencies of the waves transmitted thereover. a transmitting loop and a receiving loop conjugate with respect to said trans'mittingloop both connected to said line, means for supplying to said transmitting loop for transmission over said line a plurality of different frerpiency carrier waves each modified in accordance with an individual speech signal and means for supplying audio frequency telephonic waves to said transniitting loop.

ll A common transmission line, a network connected to said line simulating its impedance at each ol the frequencies of the 115 waves transmitted thereover, a transmitting loop and a receiving loop conjugate with respect to said transmitting loop both connectedto said line, means for selectively receiving from said receiving loop each of a phlrality of different carrier frequency speech modified waves, and means for also selectively receiving from said receiving loop audio frequency telephonic waves representing speech SlgllllS.

20. A common transmission line, a plurality of signal lines. two-way repeating means between said transmission line and certain of said signal lines for repeating speech modified carrier currents as audio 13'- cy speech currents and vice versa, "away repeating means between said isuiission iine and at least one of said i repeating audio frequency 7 t all of said two-Way repeatus having a common transmitting and common receiving circuit, said connected in conjugate relaansmission line. smission circuit, means for supnrality of different frequency etc, individual wlective means each. of said difierent fre- 1, from said circuit, and an 'nrnetrically conducting eleeach of said selective means whereby said selective dciented Irom interacting upon 21-. transmission circuit, means for supplying a plurality of different frequency urrents thereto, individual selective means selecting each of said currents from said :uit, anindividual repeater having an of high resistance connecting said selective means to said circuit,

id selective devices do not sub- "iect the impedance charactercs of said line. c A. multiplex system comprising a common transmission line, means for trans in "ti currents of different frequencies "n individual circuit for each of frequency currents, separate ns connecting each of said cirl tie in energy transfer relation,

mitting currents of said selective means comprising filters effectively connected in parallel relation to each other with respect to said line and means interposed between each of said filters and said line to prevent transmission to said line of transients originating in the respective filters.

24. A multiplex system comprising a, common transmission line, means for transdifferent frequencies thereover, an individual circuit for each of said different frequency currents, separate selective means connecting each of said circuits to said line in energy. transfer relation, said selective means comprising filters connected effectively in parallel to each other with respect to said line, and a high impedance repeating element interposed between said line and each of said filters whereby any tendency of a. filter to act as a short circuit for currents of frequencies outside its transmission range is eliminated.

25. A multiplex system comprising a. common line, means for supplying thereto a plurality of different frequency carrier currents each modified in accordance with a lower frequency Wave individual thereto, selective means for each of said carrier cur rents connected to said line, and an individual repeater of the audion type interposed between each of said selective means and the common line.

I n Witness whereof, I hereunto subscribe my name this th day of December A. D.,

BURTON \V. KENDALL.

Certificate of Correction.

it s hereby upon t e application of mprovement in Signaling Systems, an error appears i tron requiring correction as follows: Pa e 4, line 87. claim and that the said Letters the same may conform to the record of the case aperiodic read an aperiodic; yvith this correction therein that 111 the fatene Office.

1,445,141, granted Februa 13 of New York, N. f di' mi 11 the printed s cifica- 17, for the wor s and Patent should be read Signed sealed this th day of March, A. 1).,

KARL FENNING, 

